This invention relates generally to the construction of signs and more particularly to relatively large signs of the type that are formed by a flexible vinyl sign face which is drawn over and secured to a sign cabinet.
In recent years, large signs having flexible vinyl faces have been introduced and have achieved considerable popularity. Signs that are constructed with flexible face material are advantageous in several respects, most notably because they allow the sign to be constructed with a single piece face in much larger sizes than is possible with rigid face signs.
However, flexible vinyl faces present problems of their own, principally because it is difficult to achieve proper tensioning of the face material. In order to prevent the sign face from becoming unsightly due to wrinkling and/or sagging, it is necessary to stretch the sign face tautly on its frame. One way this has been done is to stretch the face on the frame in the factory and then fold or collapse the frame in accordion fashion for shipment to the job site. At the site, the frame is unfolded and secured in a rigid position on the ground and then lifted as a single flat panel and installed on the sign cabinet. This type of system is not practical for signs that are particularly long. Another major problem is that two boom trucks are required to lift the sign panel if the sign is large (over 45 feet long), and a number of workers are required to stabilize the face during installation. Because the face has a relatively lightweight frame and a large surface area, installation in windy conditions is impossible. If the face is installed at the factory, it is always possible that it will lose tautness during shipping, handling or installation. Furthermore, after the face has been installed, it is subjected to exposure to the elements which can cause it to become loose and unsightly.
Additional difficulties are encountered with systems that are designed for field installation of the flexible face. This type of system requires some type of tensioning mechanism that allows the sign face to be stretched and held in the proper tension both horizontally and vertically. Achieving the proper tension in this type of system relies on the "feel" of the worker or workers who make the installation, and poorly tensioned sign faces often result. Stripes and other graphic patterns can appear crooked or otherwise distorted if the face is too loose or maintained under more tension in some areas than in other areas.